implement support for parameter substitution via #/% operators

1 files changed, 41 insertions, 24 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 792886944..1740187d4 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -43,7 +43,6 @@
  *      Here Documents ( << word )
  *      Functions
  *      Tilde Expansion
- *      Parameter Expansion for substring processing ${var#word} ${var%word}
  *
  * Bash stuff (maybe optionally enable?):
  *      &> and >& redirection of stdout+stderr
@@ -76,6 +75,7 @@
 #include <fnmatch.h>
 #endif
 #include "math.h"
+#include "match.h"
 
 #ifdef WANT_TO_TEST_NOMMU
 # undef BB_MMU
@@ -1667,8 +1667,9 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
         char first_ch, ored_ch;
         int i;
         const char *val;
-        char *p;
+        char *dyn_val, *p;
 
+        dyn_val = NULL;
         ored_ch = 0;
 
         debug_printf_expand("expand_vars_to_list: arg '%s'\n", arg);
@@ -1844,7 +1845,7 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
                                 ++var;
                         } else {
                                 /* maybe handle parameter expansion */
-                                exp_off = strcspn(var, ":-=+?");
+                                exp_off = strcspn(var, ":-=+?%#");
                                 if (!var[exp_off])
                                         exp_off = 0;
                                 if (exp_off) {
@@ -1873,29 +1874,45 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
                                 val = utoa(val ? strlen(val) : 0);
                                 debug_printf_expand("%s\n", val);
                         } else if (exp_off) {
-                                /* we need to do an expansion */
-                                int exp_test = (!val || (exp_null && !val[0]));
-                                if (exp_op == '+')
-                                        exp_test = !exp_test;
-                                debug_printf_expand("expand: op:%c (null:%s) test:%i\n", exp_op,
-                                        exp_null ? "true" : "false", exp_test);
-                                if (exp_test) {
-                                        if (exp_op == '?')
-                                                maybe_die(var, *exp_word ? exp_word : "parameter null or not set");
+                                if (exp_op == '%' || exp_op == '#') {
+                                        /* we need to do a pattern match */
+                                        bool zero;
+                                        char *loc;
+                                        scan_t scan = pick_scan(exp_op, *exp_word, &zero);
+                                        if (exp_op == *exp_word)        /* ## or %% */
+                                                ++exp_word;
+                                        val = dyn_val = xstrdup(val);
+                                        loc = scan(dyn_val, exp_word, zero);
+                                        if (zero)
+                                                val = loc;
                                         else
-                                                val = exp_word;
-
-                                        if (exp_op == '=') {
-                                                if (isdigit(var[0]) || var[0] == '#') {
-                                                        maybe_die(var, "special vars cannot assign in this way");
-                                                        val = NULL;
-                                                } else {
-                                                        char *new_var = xmalloc(strlen(var) + strlen(val) + 2);
-                                                        sprintf(new_var, "%s=%s", var, val);
-                                                        set_local_var(new_var, -1, 0);
+                                                *loc = '\0';
+                                } else {
+                                        /* we need to do an expansion */
+                                        int exp_test = (!val || (exp_null && !val[0]));
+                                        if (exp_op == '+')
+                                                exp_test = !exp_test;
+                                        debug_printf_expand("expand: op:%c (null:%s) test:%i\n", exp_op,
+                                                exp_null ? "true" : "false", exp_test);
+                                        if (exp_test) {
+                                                if (exp_op == '?')
+                                                        maybe_die(var, *exp_word ? exp_word : "parameter null or not set");
+                                                else
+                                                        val = exp_word;
+
+                                                if (exp_op == '=') {
+                                                        if (isdigit(var[0]) || var[0] == '#') {
+                                                                maybe_die(var, "special vars cannot assign in this way");
+                                                                val = NULL;
+                                                        } else {
+                                                                char *new_var = xmalloc(strlen(var) + strlen(val) + 2);
+                                                                sprintf(new_var, "%s=%s", var, val);
+                                                                set_local_var(new_var, -1, 0);
+                                                        }
                                                 }
                                         }
                                 }
+
                                 var[exp_off] = exp_save;
                         }
 
@@ -1921,6 +1938,8 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
                 if (val) {
                         o_addQstr(output, val, strlen(val));
                 }
+                free(dyn_val);
+                dyn_val = NULL;
                 /* Do the check to avoid writing to a const string */
                 if (*p != SPECIAL_VAR_SYMBOL)
                         *p = SPECIAL_VAR_SYMBOL;
@@ -4428,7 +4447,6 @@ static int handle_dollar(o_string *as_string,
                                                 break;
                                         }
                                         goto case_default;
-#if 0 /* not implemented yet :( */
                                 case '#': /* remove prefix */
                                 case '%': /* remove suffix */
                                         if (expansion == 0) {
@@ -4437,7 +4455,6 @@ static int handle_dollar(o_string *as_string,
                                                 break;
                                         }
                                         goto case_default;
-#endif
                                 case '-': /* default value */
                                 case '=': /* assign default */
                                 case '+': /* alternative */